Top image: Dragon capsule berthed to the International Space Station for Commercial Resupply mission 4 in September 2014. Credit: SpaceX

Along with mundane holiday messiness impacting rescheduling, the space station will also be entering a phase of its orbit when it is in near-constant sunlight. This orbital state will last from December 28 to January 7, and involve thermal and operational constraints that bar the Dragon capsule from mating with the station.

The static fire test worked on December 16th without doing anything catastrophic, but it ended early, which is non-ideal. Technically, the flight could go ahead the way things are right now, but for their first real-life attempt at making the Falcon 9 boosters reusable, SpaceX is embracing an abundance of caution. Thus, the launch is delayed to give their engineers a chance to investigate what happened, and how it could impact the mission (if at all).

This is the second time the cargo run was delayed; the launch was originally scheduled for October 3rd, 2014, then slowly pushed back from December 1st to 9th to 16th to 19th until this delay into January. The space station has plenty of supplies on-hand (even after the Antares explosion cut an anticipated cargo run), and the astronauts are in no danger from the delay. When the launch finally happens, it will be the fifth Commercial Resupply mission conducted by SpaceX for NASA.